Martin Parsons is an author, writer and teacher who has a PhD in Islam and Christian-Muslim relations.

Islamic State (IS), the new name by which ISIS (Islamic state of Iraq and Syria) now calls itself, powerfully symbolises the organisation’s aims. In common with other Islamist groups, its ultimate aim is to see not just one area, but ultimately the entire world subject to Islamic government with sharia: i.e, Islamic law enforced on all peoples – Muslim and non Muslim alike. That is the central truth we need to grasp about IS.

That is why there is now a real risk that both Iraq’s ancient Christian population dating from the first century, and its even older Yezidi population estimated at half a million people, will be quite literally exterminated – at least as far as their presence in their Iraqi homeland is concerned, a fate that has already overtaken the country’s ancient Jewish population in the last 50 years. In 1987, there were 1.4 million Christians in Iraq. By 2003 it had fallen to 350,000 and is thought to have halved since then, primarily due to Islamist violence.

However, what we are seeing in Northern Iraq with the attempted forcible conversion of entire Iraqi Christian and Yezidi populations is not a new phenomena. Look back to the nineteenth century:

Similar forced conversions occurred among the non-Muslim tribes of the Hindu Kush following the Durand agreement of 1893 by which the British handed this area over to the Afghan amir, Abdul Rahman Khan. The amir immediately sent his troops into the area, where, within three years, the animist tribes, estimated to have been 195,000 people, were all forcibly converted to Islam – quite literally at the point of the sword.

One can also find similar examples in the broad region occupied by the Kurds, then part of the Ottoman Empire. The ancient Christian communities there lived under millat status, a second class citizenship that allowed Christians and Jews to continue to exist as communities, provided that they agreed to submit to Islamic government and sharia symbolised by them paying the jizya – an extra tax on non Muslims stipulated in sharia.

Sharia itself designated them as dhimmis – an underclass excluded from many of the legal rights enjoyed by the majority community with, for example, a Christian’s word being given only half the weight of a Muslim’s in court, a situation which still today leads to a multitude of injustices in countries where sharia is enforced. Refusal to pay the jizya was seen as an act of treason deserving death. So, for example, in 1843, when the British consuls in Van (now Eastern Turkey) and Mosul (now Northern Iraq) encouraged the Assyrian Christians not to pay the jizya, an estimated 10,000 Assyrian Christians were massacred and others sold into slavery by local Muslim Kurdish rulers with the overt complicity of the Ottoman government.

What is noteworthy about these examples is that they occurred in the nineteenth century before the advent of modern Islamism. They represent a strand of Islam that can be traced back at least as far as the medieval theologian Ibn Taymiyya (b.1328) that emphasised sharia enforcement and the imposition of Islamic government on Muslim and non Muslim alike. Throughout much of Islamic history this view has contrasted with that of a large number of Muslims who have seen Islam primarily in devotional, rather than legal and political terms. However, it is important to understand that that the form of sharia that modern Islamists such as IS are seeking to enforce varies only in details from the medieval textbooks of sharia that are still taught in madrassas around the world.

For example, the Hedaya, which is the main sharia textbook taught in madrassas of the Hanafi school that predominates in the Turkey-Syria-Iraq region, states that where jizya is not voluntarily submitted to by non-Muslims it should be enforced, referring to a verse from Surah 9 of the Qur’an:

Those who do not believe in Allah and the Last Day – even though they were given the scriptures, and who do not hold as unlawful that which Allah and His Messenger have declared to be unlawful, and who do not follow the true religion – fight against them until they pay tribute (jizya) out of their hand and are utterly subdued. (Q9:29)

Sharia essentially understands jizya in terms of it being ‘protection money’ – indeed jizya is often translated with precisely this term (see the English Qur’anic translations by Ahmed Ali, Ali Unal and Farook Malik). However, it also stipulates that this ‘protection’ only applies to monotheists, principally Christians and Jews – i.e: those who ‘were given the scriptures’. It does not apply to groups deemed to fall outside this category, which is why the Yezidis are currently being massacred by IS.

Similarly, the command to ‘fight those who do not believe until they submit’ is almost certainly why IS has just beheaded US journalist Daniel Foley. For Islamists such as IS, the act of beheading is the way executions were carried out in early Islam, a pattern increasingly followed since the 2002 murder of Daniel Pearl.

Unless we understand what motivates people like IS in Northern Iraq and Syria, then we cannot hope to develop a strategy to protect those such as the Iraqi Christians and Yezidis who suffer from their murderous violence. If we do not understand this, then all that we will have is a collection of humanitarian, political and possibly military tactics – and as the great Chinese general Sun Tzu, observed in his sixth century BC classic The Art of War:

“Tactics without strategy is simply the noise before defeat.”

That strategy needs to focus on the need to contain and where possible reverse the increasing spread of sharia enforcement around the world. In this respect, we can roughly divide the history of Islamic countries since World War Two into three eras:

In the first era from 1945 up until the late 1970s, western style law inherited from colonial administrations was given far more authority than sharia, even though at a local level many people still used sharia to settle personal legal matters.

The second era dating from the 1970s saw a growing enforcement of various aspects of sharia, particularly inspired by the Iranian revolution in 1979. The result has been increasing suffering for both non-Muslim minorities, liberal Muslims and, for that matter, many ordinary Muslims who view Islam primarily in devotional terms, and just want to get on with their family lives.

The enforcement of sharia in many, though not all, such situations, has not yet reached the extent of that imposed by groups such as the Taliban and IS, due to the continuing presence of dual legal systems of western law and sharia. However, sharia has been becoming increasingly predominant, with almost all countries having sharia clauses in their constitutions, which in many instances allow sharia judges to strike down parliamentary laws judged to be incompatible with sharia.

The third era dates from the 1990s, which was the time when radical jihadist groups began to use extreme violence to seek to enforce sharia on entire population areas. Such groups include al-Qaeda and the Taliban in Afghanistan and Pakistan, Boko Haram in West Africa, al-Qaeda in the Islamic Maghreb (AQIM) in North West Africa, al-Shabab in East Africa and, more recently, Islamic State in Northern Iraq and Syria. This third era presents a direct security threat to the West, as once the full Islamic state with sharia enforcement is established it becomes a base from which to launch major jihadist attacks on non Muslim countries, a situation which we saw all too clearly with al-Qaeda in Afghanistan.

The second and third eras do of course overlap to a significant extent. However, the overall pattern is one of an increasing spread of sharia enforcement in recent years. If we take just the last three years 2011, 2012 and 2013, sharia enforcement has spread markedly around the world, with different Islamist groups using either political or violent means to achieve this.

What is needed is not a series of tactics to deal with individual incidents such as the current tragedy facing Iraqi Christians and Yezidis, but an overarching strategy. If we have this then, when events such as the massacres and forced conversions of Yezidis and Christians in Northern Iraq occur, as tragically they almost certainly will again in the not too distant future, then we only need to discuss the tactics to deal with it, not dither over the broader questions of whether or not we should act at all.